charm production at large rapidities in pp and dau collisions at rhic
DESCRIPTION
Charm Production at Large Rapidities in pp and dAu Collisions at RHIC. Xiaorong Wang for PHENIX collaboration New Mexico State University. gold. deuteron. North Muon arm : 2.4 > h > 1.2. South Muon arm : -1.2 > h > -2.0. The PHENIX Detectors. PHENIX Preliminary. Direction. Au-going. - PowerPoint PPT PresentationTRANSCRIPT
April 21, 2006 X. R. Wang, DIS2006, Tsukuba, Japan 1
Charm Production at Large Rapidities in pp and
dAu Collisions at RHIC
Xiaorong Wang for PHENIX collaboration
New Mexico State University
Xiaorong Wang, SQM 2006 2April 21, 2006
The PHENIX Detectors
South Muon arm : -1.2 > > -2.0 North Muon arm : 2.4 > > 1.2
golddeuteron
Xiaorong Wang, SQM 2006 3April 21, 2006
Physics Questions
Cold nuclear medium effects: Parton distributions
gluon (anti)shadowing CGC
Interactions with medium Parton energy loss QCD Power Correction
Recombination
New probes: Charm
PHENIX Preliminary
Au-goingd-going
Direction
High pT light hadrons
Xiaorong Wang, SQM 2006 4April 21, 2006
Gluon Shadowing in Heavy Nucleus
X
y
yield
Universal
)(ˆ)()( 2121 zDdxFxFd QQxxQQpp
From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.
Xiaorong Wang, SQM 2006 5April 21, 2006
Shadowing at Forward rapidity in dAu collisions
Color Glass Condense Dynamic Multiple
Scattering Power Correction
J. Qiu & I. Vitev
D. Kharzeev & K. Tuchinhep-ph/0310358
Power correction only
CGC
Xiaorong Wang, SQM 2006 6April 21, 2006
Recombination
“Explains” light hadron yields in forward and backward rapidities Input: low pT forward
/backward hadron distributions
Expect similar effects on open charm(?)
Measurement of charm yields could provide additional constrains on these models
H
Xiaorong Wang, SQM 2006 7April 21, 2006
Prompt µ background subtraction
Punch-through hadrons: Data driven method to Estimate
attenuation
Decay muons: Vertex distribution analysis
Open Charm Analysis Techniques
Decay muons
Punch-through hadronsPrompt muons ?
Gap2 Gap3 Gap4
Prompt+decay muons
Hadron
num
ber
of
trac
ks
00 37.0)( NeNiNiL
Muondetector
absorber
decay
punchthrough
prompt
Xiaorong Wang, SQM 2006 8April 21, 2006
Comparison Prompt - pt spectrum with theory
FONLL: Fixed Order next-to-leading order terms and Next-to-Leading-Log large pT resummation.
FONLL and PYTHIA calculation under predicted PHENIX Data at forward rapidity,
Run2pp -
FONLL: Solid line and bandWithout scaling the charm contribution: dotted linembsyspythiasysdata
statdy
dy
cc
).(.).(105.0
.)(013.0243.0|
049.0087.0
6.1
Xiaorong Wang, SQM 2006 9April 21, 2006
Prompt ’s pT spectra in dAu collisions and RdAu
North Arm: d going direction;
South Arm: Au going direction
Xiaorong Wang, SQM 2006 10April 21, 2006
How about J/Psi?
_NO_ Recombination! Gluon shadowing/saturation Initial state parton energy loss J/Psi final state nuclear
absorption has minimal effects on the shape
X
RdA
0
0.2
0.4
0.6
0.8
1.0
1.2
Xiaorong Wang, SQM 2006 11April 21, 2006
Shadowing or Energy Loss ?
)1972( ppdA
Shadowing is not enough
Initial state energy loss? Incoming gluons
loss energy before the hard collisions
Affects low pT particle production in the FWD and BWD papidities
Xiaorong Wang, SQM 2006 12April 21, 2006
pT broadening: Cronin Effect
Broadening of J/ pT distribution suggests initial scattering (maybe also energy loss) is important
Xiaorong Wang, SQM 2006 13April 21, 2006
Summary and Outlook Physics at Forward and Backward Rapidity:
open charm J/psi
Observed: heavy ~ ligh hadrons suppression in the forward enhancement in the backward
Causes for such effects are not very clear Shadowing: CGC, Power correction Initial state energy loss recombination Need more theoretical work
Need/Like to have: Lower energy dAu collisions: stay away from shadowing regions Explore { x, Q, sqrt(s) } space -> (y, pT, sqrt(s)) experimentally
Parton energy loss vs shadowing pT evolution – shadowing vs power correction Shadowing vs recombination
Explore QCD dynamics in details in coming years!
Xiaorong Wang, SQM 2006 14April 21, 2006
Backup
Xiaorong Wang, SQM 2006 15April 21, 2006
Sources of prompt muons (pT> 0.9GeV) (determined from Pythia)
D±±, … , c++,
B± ±
± ±
* + -
q q * + -
J/,… + -
, , + -
charge asymmetric
charge symmetric
Xiaorong Wang, SQM 2006 16April 21, 2006
Nuclear Modification Factor: RdAu (decay from light hadrons)
PHENIX Preliminary PHENIX Preliminary
Au-goingd-going
Direction
RdAu vs pTRdAu vs η
Xiaorong Wang, SQM 2006 17April 21, 2006
Experimental Challenge
Prompt Muons
Punch-through hadrons
Decay Muon
Xiaorong Wang, SQM 2006 18April 21, 2006
PHENIX muon arms “x” coverage
From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.
gluons in Pb / gluons in p
X
PYTHIA open charm simulation
Particle production in the d direction (north) is sensitive to the small-x parton distribution in the Au nuclei; whereas in the gold (south) is sensitive to the large-x in Au
Xiaorong Wang, SQM 2006 19April 21, 2006
Xiaorong Wang, SQM 2006 20April 21, 2006